Environmental pollutants are all around us — from pesticides to air pollution to naturally occurring metals in the food we eat, these substances can profoundly affect our health.

For frequent travelers, there's another substance in the air that might cause concern: space radiation, defined as the cosmic energy traveling through space in the form of high-speed particles and electromagnetic waves, according to NASA.

(ABOVE: Airplanes Silhouetted by Sun and Moon)

Space radiation is a particular health concern for astronauts, according to NASA; but for the rest of us, it still may pose a problem.

“Even if you go up a mountain or tall building, there is less atmosphere and you experience higher levels of space radiation,” Nathan Schwadron, Ph.D., associate professor of space plasma physics at the University of New Hampshire, told Weather.com. “The minute you take off in an airplane, you’re moving up in altitude. The higher you move up, the higher levels of radiation."

The average U.S. citizen is exposed to 620 millirems (mrem — a unit used to describe common dosages of radiation) a year, according to the U.S. National Council on Radiation Protection and Measurements. The minimum number of yearly exposure linked to an increased risk of cancer is 10,000 mrem, according to the United States Nuclear Regulatory Commission.

For perspective: A round-trip flight from NYC to LA only contributes five mrem, which isn't a lot.

“If you go up in an airplane, the levels of radiation that you are exposed to are less than .001 rad [a unit used to measure the amount of absorbed radiation] per day,” said Dr. Schwadron. “So you’d have to be up in flight for 24 hours to get .001 of a total dose [1 rad]. You’d have to fly continuously for decades to get levels of radiation that would start to be around the limit.”

Even the most frequent passengers might have little to worry about compared to patients who receive even one CT scan, which is 1,000 mrem.

At a population level, some frequent fliers will inevitably face a higher cancer risk, Dr. Schwadron said. But the actual danger is minimal. “The chances of something else happening — like getting hit by a car — is a million times higher,” he said.

Plus, humans are equipped to fight off the negative affects of radiation. “There’s a certain amount of voodoo associated with radiation, but the reality is since the 1940s we’ve learned a lot about it, and what we know is that it’s very natural,” Dr. Schwadron said. “Our bodies have a whole defense system built up to fight off radiation ... exposure to low levels is fairly natural and is very much a part of the evolution of any biological system.”

The best way to lessen the risk of all forms of radiation, space or otherwise: healthy living.